The founder of a powerful charter school network who has long been at odds with Mayor Bill de Blasio Thursday ended speculation that she would challenge him in the next election.

"I am not running for mayor in 2017," Eva Moskowitz, founder and CEO of Success Academy Charter Schools, said at a news conference on the steps of City Hall. "My decision is not based on my estimation of winnability. Politics is a pretty unpredictable thing."

As she spoke, protesters with New York Communities for Change heckled her from across the plaza, denouncing Success Academy for taking contributions from hedge funds. Some complained Moskowitz runs her schools too much like a corporation.

"Hey, Eva, get off it," they chanted. "We're for children over profit."

Moskowitz told reporters she wanted to focus on improving public education. "This kind of transformational change may be a once-in-a-lifetime opportunity, and I believe our kids are worth it," she said.

Moskowitz, a two-term former City Council member, would not rule out a 2021 run.

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"I like politics," she said.

She has feuded with de Blasio over his plans to rein in the publicly funded, privately run charter schools and focus on traditional public schools.

"I don't think that Mayor de Blasio is to blame for the educational crisis," she said. "I do think the mayor has to be held accountable for his solutions."

Moskowitz also has tangled with the United Federation of Teachers, and she envisioned Thursday that being the city's chief executive would mean "four years of dueling press conferences" with union president Michael Mulgrew.

De Blasio, who has said he will run for re-election in 2017, said at a separate unrelated Queens event of Moskowitz: "She's made her choice," and added that he welcomes other candidates for "spirited debate."

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The Rev. Michel Faulkner, a Harlem minister and former Jets player, has announced he would challenge de Blasio in 2017, as a Republican.